Brake



31111625, l945 R. A. GoEPFRlcH ErAl. 2,379,144

BRAKE Filed May 27, 1942 2 Sheets-Sheet 2 ATTORNEY VFig. i;

Patented June 26, 1945 UNITED s'r-A'rss PArENjr. orrlcl-:r

W. White, Van Nuys, galli., assignors to Bendix Aviation Corporation, South Bend, Ind., rcorporation of Delaware Appuoauun May 27, lsiafserial No. 444,636

4 0mm. qui. iss- 106) This invention pertains to brakes and particulariy to the type of brakes employing a plurality lof connected shoes whichare fully iioating in the sense that they shift to anchor through.` one shoe or another depending upon the direction of rotation of the brake drum.

An object of this invention is to provide,'lin a brake having a pair of shoes and having an adjusting `strut between the shoe ends, mechanism for spreading the shoes by utilizing the adjusting strut as a shoe spreading strut, this brake applying mechanism being preferably used as the parking brake or emergency brake applying mechanism in addition to service brake applying means. A second object oi' the invention is to position the shoes of a full floating' brake horizontally i. e. with vthe ends of each shoe on a horizontal line, and to provide means for supporting the shoes. The advantage of so positioning the shoes-is that it simplifies the problem of keeping arcuate brake shoes concentric with a circular brake drum.

' Other objects are to so-arrange the parking or emergency brake applying mechanism that a substantially horizontal pull may be exerted thereon by a cable or other means connected to an operator operated member, and to provide parking or emergency brake applying mechanism which is adjusted by an adjustment oi the service brake applying mechanism and in which the slack need not be taken up separately from the service brake.

positioned between `the shoes at one end thereof for applying a spreading force thereon. As shown the hydraulic motor also serves the purpose oi anchoring the shoes during application of the brake. "The anchoring'is. accomplished through` the pistons II and l1 of the motor, an anchoring.l

. ring IB positioned in a groove inside the cylinder;

. hydraulic motor l5, adjusting strut or link 22 .is

provided to connect the shoes. 'Ihe adjusting strut 22, which can be seen clearly in Fig. 2, is! of a type well known to the art and jcomprlses a sleeved member 2S v forked at Etta receive the web of shoe It and internally threaded along its internal surface 25; a screw 26 having a threaded portion 21 entering the sleeve member 28, a serrated head 26 which can be turned to change the position of the screw v'relative Vvtc'cthe Sleeve member. 23, and a guide portion 253 on the side 'of the head opposite thethreadecl stem 2l; and

a screw supporting member Si having a recess 3i to receive the guide portion 2@ of the adjust- 30-shoe i3. y

Other objects and advantages of my invention will become apparent during the following description, in which reference will be had to the accompanying drawings:

Fig. 1 `is a vertical section of a brake applying assembly taken on arplane just inside the head oi the brake drum and showing my improved brake;

Fig. 2 is a section taken on the line 2 2 oi Fis. 1: y v

ing screw and a notch 32 to receive the web of The brake thus 'far described is of -a type Well known to the art and its' operation need n'ot be described in detail. Suice it to say that. depending upon the direction of drum rotation at the time the hydraulic motor iii is actuated, one of f shoe through the adjusting strut 22. When the i0 the position of the shoes to compensate for shoe 7" Fig. 3 is a section taken on the yline 3 3 of Fig.l 4 isal section taken on the line i-il or Fis. 3; i, Fig. 5 is a.section taken on the line 5-5 of Fig. l; and v Fig. 6 is a section disclosing a'modincation of lthe hydraulic motor .applying device oi Fig. l.

The brake shown in Figures l1-5, inclusive, corn-l prises generally a rotatable brake drum il, a nonrotatable support or backing 4plate JI, and two arcuate brake shoes i3 and MIl so positioned that the two ends of either shoe-lie on a, substantially horizontal line. A `hydraulic motor It may be brakes are released and it is desired to adjust.

lining wear, the adjusting screwl 26 may be rotated to increase the distance between the ends i of the shoes. The brake described thus far does diier in at least one respect from other brakes operating on similar principles but not in a like manner, in the respect that the hydraulic applyone another, to hold them in their proper position concentric with `the brakev drum. Should the' brake shown and described 'herein be positioned vement', it would be extiemeiyhsrd 'to keep the s ces from. dropping downward from the in-` hiluence of gravity and thereby-disturbing their adjacent the adjusting strut 22.

concentricity. Because the shoes are horizontal and -at the same time are fully oating, it is necessary to provide. a support for the shoes at the end of the shoes away from the anchor and The support which is shown in detail in Figs. 3 and 4 comprises 'a lever- 33 pivoted on a pin 34 fastened on the backing plate, connected at 35 to a spring 36 which is also connectedby a pin 31 to the backing plate.. The lever has an integral nib 33a which extends into'an arcuate groove cut in theV head of pivot pin 3l. The washer is` fixed against rotation about the pivot in order that contact of the nib with the ends of the arcuate groove willl limit movement of the nib. In the position shown in Figs. 1 and 4, the nib is held by the spring against the upper end of the groove. The pivot pin 34 may be so positioned as to initially adjust the position of theshoes after which it is held tightly in `place by suitable means. The positioning lever 33 contacts theVA rim of shoe I3 and thereby prevents the weight ofshoe I3 from pulling it vertically downward, and through spring 20, prevents the weight of shoe I4 from pulling it assembly tobe connected at 40 to the end of a brake applying able 4I. When the cable 4I is put under tension to apply the emergency or parking brake it draws the lower end of lever 31a..

toward the left (as seen in Fig. 1)l thus exerting a force through pivot 38 tending to move shoe I3 of the brake drum to be that'indicated by the arrow in Fig. 6, shoe 56 will 'be the anchoring or secondary shoe and shoeS'I will be the applying or primary shoe. With the arrangement shown, the secondary shoe will never leave its anchored position during forward rotation of the brake drum. Y

Being aware of the possibilities of modifications in the particular structures herein described without departing from the fundamental principles of our invention, we do not intend that :their scope be limited except as set forth by the brake applyagainst the brake drum and a force through adjusting strut 22 tending to niove shoe Il against:

the brake drum. During such emergency application, the shoes both pivot on the pistons of hydraulic Amotors I 5 and apply as in an ordinary non-servo brake. Because -the various parts'of the brake-are positioned as shown, it is particularly easy and convenient to apply the parking or emergency brake. This is true inasmuch as a substantially horizontal applying ,force may be exerted through cable 4I to .swing lever 31a. Lever 31a without obstructing'the center of the brake assembly exerts an applying force effective toy spread the brake shoes. Becausey the parking or emergency 'brake is applied through the adjusting structure, adjusting theposition of th'e shoes by operating the strut does not develop -any slack in theparking brake applying mechanism, but instead automatically accomplishes adjustment of the v.parking brake whenever. the position of thevshoes is 'changed to cause the service brakes to be effective Without' excessive travel of .the pedal or other operator operated member. y j Y o In Fig. 6is shown a modified hydraulic motor.

A valve arrangement is used to make the primary piston move before the secondary piston. The inlet`to the 'motor is' shown at 5I. Because of the presence of a valve member 52 between the inlet and piston 53', hydraulic uid under pressure admitted to the motor will move piston El before itfmoves piston 53, said piston 5,3 not being sub- Ajected to pressure until such pressure overcomes a spring 55. 'Assuming the direction of rotation motor between the shoes at one end thereof..

adapted to exert an applying force on the shoes, a vertically extending adjustingfstrut between the shoes at the other end thereof, means at the motor end of the shoes for receiving the anchoring torque of the shoes, and mechanical means for applying the shoes including a lever pivoted on one of the shoes andon one end of the adjusting strut to exert a spreading force on the shoes through its pivot and through the adjusting strut. l

2. A brake comprising a rotatable brake drum. two horizontally extending brakey shoesV adapted to cause friction tending to impede rotation of the drum, said brake shoes together constituting a full floating friction element, anchoring 'and applying means between the ends of the shoes at one side of the`drum, a floating adjusting strut between the shoes at the other side of the drum, a lever pivoted on one ofthe shoes and on one end of the adjusting strut, a cable extending substantially horizontally adapted to swing the lever to spread thel shoes at the adjusting strut side of the drum, and means at the adjusting strut side of the drum for .vertically supporting the ends of the shoes and the adjusting strut. o

-3. A brake comprising a rotatable brake'drum, a xed backing-plate, two horizontally extending brake shoes adapted to cause friction tending to impede rotation of the drum, said brake shoes tcgether'constitutin'g a full floating friction element, anchoring and applying means between the side of the drum, a lever'pivoted on the backingplate, and in contact with the end of the -upper shoe, and a spring in tension between the lever and a projection on'the backing-plate, the movement ofv said lever about its pivot being limited.

4.- A brake v,comprising a rotatable brake drum, two arcuate brake shoes adapted to cause friction tending to impede rotation of the drum, anchoring and applying means between the shoes at one end thereof, a floating adjusting strut located between the shoes at the opposite end thereof and pivotally connected to both of said shoes, the two shoes and adjusting strut thereby constituting a full'iloating friction element, a lever pivoted on one of the shoes and on one end of the adjusting strut, and means for swinging the lever to cause nUDoLPH A JonN w. wm'rn by spreading the unanchored ends of the shoes. i e 

